<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 1. 一个200*200的div在不同分辨率屏幕上下左右居中，用css实现(1.html) -->
    <style>
        div {
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            width: 200px;
            height: 200px;
            margin: auto;
            background-color: #bfa;
        }
    </style>
</head>

<body>
    <div>

    </div>
</body>

</html>